A solution of ethyl 3-[3-methyl-3-(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalen-2-yl)-2,3-dihydrobenzofuran-5-yl]acrylate (320 mg, 0.74 mmol), water (40 μl) and sodium hydroxide (240 mg, 6 mmol) in THF is heated to reflux for 24 h. The reaction mixture is poured onto an AcOEt/water mixture, acidified to pH=1 with a concentrated hydrochloric acid solution, and extracted once with ethyl acetate. After separation the organic phase is washed twice with water, dried over magnesium sulphate and concentrated in vacuo at 40° C. in a rotary evaporator. The solid obtained is crystallized in heptane.
